Picturesque Port Isaac provides the beautiful wintry backdrop for this festive special, with all the regular members of the cast reprising their roles. Portwenn is full of festive fun, until Doc Martin has the grotto closed down because he fears Santa has something contagious.

Portwenn is full of festive fun, until Doc Martin has the grotto closed down because he fears Santa has something contagious, upsetting the children, including his own son James. While awaiting the results of the tests to find out why Leonard is so itchy the Doc tells him he cannot be Santa until they have the diagnosis.

Leonard is determined to show the Doc the magic of Christmas, and tries to deliver the Ellingham's Christmas presents down the chimney. Martin is furious, and remonstrates with Leonard for putting himself at risk on the roof of their house, unaware James has witnessed it all. James decides to run away to find Santa, but Ruth bumps into him and persuades him to have breakfast, given the journey to the North Pole is a long one.

To try to make up for James' disappointment at not meeting Santa, Louisa decides, with the help of the village, to arrange a lantern parade, led by Santa, something she has fond memories of from when she was a child in Portwenn. PC Joe Penhale is thrilled to be asked to don his Santa suit and lead the parade.

But parish councillor Agatha Higgins, objects to the plan, because the event doesn't meet certain requirements, not least the health and safety risks. Louisa tries to change her mind by inviting her to their parade meeting on the Platt where Christmas preparations are in full swing. Agatha seems to be getting into the festive spirit when she guesses the weight of the turkey, but before she can confirm the parade can go ahead, she trips and hits her head on the floor, and an ambulance has to be called.

A delighted Mrs Tishell finds herself under the mistletoe with the Doc after he notices her choking for a second time. Fearing she has a serious illness and that this might be her last Christmas, she just can't resist stealing a Christmas kiss. Martin is appalled by her advances, but as a result diagnoses her with a manageable condition, not a life threatening illness. He also tells her the prolapsed disc has healed, so she no longer has to wear her neck brace. But Mrs Tishell is not sure she wants to abandon the neck brace.

Morwenna can't help but have a seemingly irrational liking for the turkey, naming it Toby. After Agatha guesses the correct weight, Morwenna decides to take it to the butcher herself. Al doesn't believe her when she says the turkey escaped on the way to the butcher, but her reasoning quickly helps him understand why she set it free.

Meanwhile PC Joe Penhale's romantic attempt to woo Janice by showering her with gifts backfires when she thinks she is being stalked.

Martin is called out to see Leonard (Santa) who has had an accident, and as he is anaemic he cannot afford to lose any blood. As Martin is driving to Leonard's house the weather is getting worse and he has an accident, which causes him to hallucinate about his mother, prompting some of his own parenting concerns. Eventually making it to Leonard's house and recovering from the cold, he treats Leonard. Leonard confides in Martin about the death of his wife and why he celebrates Christmas. He challenges Martin to do the same. But will they make it back to the village in time for the Christmas parade Louisa has organised?